If Serena Williams and Jennifer Capriati had been waging a world title fight - and there were times when you would have been forgiven for believing they were - you might have guessed that the big punch that changed everything came in the 12th round - or rather the fourth game of the second set.
Capriati, lifting herself brilliantly from under the weight of eight successive defeats at the powerful hands of the world No 1, had swept the first 6-2 in just 27 minutes and was serving, with impressive precision, to stay level at 2-2 in the second, when she engaged in one of a series of superb rallies.
This one, however, it seemed clear enough at ringside, proved to be the big one; both players racked the court with forehands and backhands one-twos, and just when it seemed that Capriati had again manoeuvred the reigning champion to the point of breakdown, Williams produced a superb running drop shot.
For a second there was silence in the ring, then a tremendous roar and a sense that the woman who has done to women's tennis pretty much what her southern Californian compatriot Tiger Woods has done to golf, had once again taken an unbreakable grip.
Williams, women tennis's most formidable physical presence, had produced a moment of perhaps decisive delicacy and afterwards you had to ask the beaten Capriati - she eventually went down 6-2, 2-6, 3-6, in one hour 40 minutes - if that indeed was the moment she knew once again that she couldn't win.
She said: "Not really because I know she's gonna play great points and we are going to have great rallies like that - but you know I won some of them, too. The real big thing was the serve, her serve, and you know she came in with some very big forehands. But I came right back at her with some other great shots that I don't think she expected."
If the Centre Court had been overwhelmingly in favour of Capriati - in a way, it needs to be stressed, much less offensively than the Roland Garros crowd who turned against Williams so viciously at the French Open - there was perhaps a compelling reason. It is that Williams wins - relentlessly, and few leading sports figures have fought so hard to re-establish themselves as the 27-year-old Capriati.
Here, for a dazzling half-an-hour or so, it seemed that the girl from Florida who seemed such a classic victim of the tennis syndrome which has disfigured the lives of so many young women, was making another significant stride away from those sad says when her life was plagued by drugs problems.
Already the winner of three Grand Slam events since her rehabilitation, here with more vigour than ever before she was fighting to take Wimbledon and topple the 21-year-old woman who dominates the game. At one point Williams was plainly in some disarray - a situation highlighted when she bent to the turf to reclaim a large gold ear-ring.
But as Capriati conceded, it is one thing to get Serena on the ropes and quite another to put her away. Capriati said: "You know I think I did better than ever before in the run of defeats to her. There were times when I really believed I could beat her and that I had surprised her with my game today. But you know in the end there was a lot that I couldn't do. I mean she was just serving so hard - I've got to give her all the credit for that. My encouragement is that I think she had to play her best tennis out there to raise her game completely to beat me.
"I certainly didn't give her the game and in the end I held on to my serve great. I was just saying to myself in that last set, this is the Wimbledon quarter-finals. I've been playing a great match, I am just going to give it my all - right here."
She has an engaging manner in defeat, the kind which might be identified by any parent of a wilful girl who has come through storms and knows, finally, what she wants. However, there will inevitably be a sniff of controversy around certain of her reactions to this defeat. She was invited to announce her conqueror as the best player she had ever played, but after a few moments of plainly deep thought she couldn't do that, and it may just have had nothing to do with a well-known lack of warmth between the players. "Serena is still playing," Capriati said. "So it is hard to make that judgement. She has so much power and she wins a lot of games with that. I would have to say that from baseline to baseline the best players I've met are Steffi Graf and Martina Hingis."
She was more circumspect, though when asked about her relationship with her No 1 fan, the Canadian actor Matt Perry, star of the Friends series. "He's just a friend," she said. "But it was nice that I had him jumping out of his seat a few times."
Meanwhile, Serena Williams, her gold ear-ring restored and secure, was playing doubles and, on this occasion, losing. However, as Capriati said, she will be playing for a long time... And winning a lot more titles. Capriati's glory yesterday was that for a good half-hour she put that reality in some doubt.
Serena Williams (US) v Justine Henin-Hardenne (Bel)
Venus Williams (US) v Kim Clijsters (Bel)